This invention relates to the structure of areas for equestrian activities in which horses can, for example, be exercised, trained or take part in competitive activities. In particular the invention relates to arrangements in which an upper equestrian surface is supported by a sub-surface layer.
It can be important to regulate the water content of an equestrian surface. It is important to ensure that the surface is not too dry or too wet. A dry surface may be too hard and a wet surface may be too soft and/or slippery. In addition, dry surfaces can become cracked, uneven or ridged. A surface that does not have a suitable water content, being either too wet or too dry, can cause injury to both horses and riders and/or hinder performance.
It is known to provide a layer of sand beneath an upper equestrian surface and to provide the sand with a drainage pipe to drain off excess water from the sand. In addition, one or more pipes can be located within the sand to provide a supply of water from a storage tank to top up the water content of the sand when it becomes too dry. Moisture sensors or water level sensors detect when the water level is too low and a pump pumps the water from the storage tank or from a water main or other water source to the pipes in the sand. However, such a system is not self-regulating (sensors and pumps are needed) and requires some form of power to drive a pump to transport water from the storage tank.
Another important aspect of equestrian surfaces is the consistency of the structural performance of the surfacing layers to provide consistency in the usage of the surfacing such that the performance of a horse is neither artificially enhanced nor impeded. Consistent structural behaviour also avoids injury to horses travelling on the surface; inconsistent structural performance can lead to lameness in horses. A key element in achieving consistent structural performance is the sub-surface layer upon which the equestrian surfaces are laid. For the sub-surface layer it is known to use combinations of granular materials mixed to provide the desired structural performance, e.g. compaction. However, such granular materials are variable in property and the structural behaviour of one mix can vary widely from another and this can lead to inconsistencies in the performance of the overlying equestrian surfaces.
The present invention is concerned with a number of new structures which allow for more effective regulation of the water content of an equestrian surface and consistency in the performance of the surface.
JP 08-000110 A discloses a system of pallets for supporting and transporting real lawn inside a multipurpose dome. The pallets each comprise an upper holding portion which holds or supports the lawn on a support plate. Beneath this holding portion is a hollow part which contains air, and sponge for holding water. The sponge is connected to the earth and sand of the lawn via a so-called pump part. The pump part is formed from so-called pumping material which is made of cloth and passes through a hole in the support plate of the holding portion. The pump part transports water from the sponge to the earth and sand of the lawn by capillary action. Similar pump parts are also provided to transport water by capillary action between adjacent pallets.
However, a disadvantage with the system of JP 08-000110 A is that no means are provided to allow water to pass down from the lawn into the hollow part. Furthermore, water cannot drain out of the hollow part. In JP 08-000110 A, water can only pass up from the hollow part to the lawn. This may not be a problem in a multipurpose dome, where there would not be any rainfall. However, it does mean that the system of JP 08-000110 A is unsuitable for use outside where precipitation would inevitably fall at some point on the system and could cause water logging.
The pallets of JP 08-000110 A require a firm supporting base (e.g. a sub-base layer or concrete slab) on which to place them. They could not, for example, be located directly on earth since the pallets could then move relative to one another (due to differential settlements in the earth beneath), leading to an uneven surface.
In the field of construction generally, it is known from WO 02/14608 to form a sub-surface layer from a structural module instead of traditional particulate materials such as natural aggregate or sand. The preferred module is cuboid in form, and may, for example, be moulded from strong plastics. In a preferred arrangement each module is formed from a top half which includes a top wall and the upper part of a peripheral sidewall, and a bottom half defining a bottom wall and the lower part of the peripheral sidewall. The top and bottom halves may each be provided with a set of half-pillars extending towards one another, the two sets of half-pillars co-operating with one another to form pillars extending between the top and bottom walls to resist vertical and lateral crushing of the module. The top and bottom halves may be two integral plastics moulded components which are fitted one inverted on top of the other. Preferably, the module further comprises a network of bracing members extending between the pillars within the module to resist deformation of the module in a horizontal plane. In the preferred arrangement the walls and network have apertures formed therein to allow water to flow both vertically downwards and horizontally through the module, for drainage purposes.
In WO 2009/030896 filed on 3 Sep. 2008, published on 12 Mar. 2009, which was not published as of the priority date of the present application and in respect of which there are inventors in common with those of the present application, there is disclosed a structural module comprising a load bearing base unit and porous material, wherein the base unit has a top wall and a bottom wall spaced therefrom by one or more supporting elements so as to define a volume between the top and bottom walls, the base unit being provided with apertures to permit the flow of liquid into and out of the volume, and wherein the porous material is a foamed polymeric material which occupies a substantial portion of the volume within the base unit and absorbs and retains substantial quantities of water that pass into the enclosed volume through the apertures. In preferred embodiments the modules are as described in WO 02/14608, but with the addition of foam blocks within the modules.